A photo-nanoimprinting method is, for example, as described in Non Patent Literature 1, one method for fabricating a resist film having a predetermined pattern shape on a substrate such as a base material to be processed, and has the following production process of (a) to (d):                (a) a disposing step of disposing a resist (photocurable composition);        (b) a mold contact step of bringing the photocurable composition into contact with a mold on whose surface a fine protruding and recessed pattern is formed;        (c) a light irradiation step of irradiating the photocurable composition with light; and        (d) after the light irradiation step, a mold releasing step of separating the photocurable composition from the mold.        
Here, the pattern shape of the resist film fabricated through the above production process of (a) to (d) is formed by transferring the protrusions and recesses of the mold to the resist film disposed on a substrate.
Here, in utilization of the photo-nanoimprinting method, reduction of a force needed to separate (mold release) the mold from a cured resist in the mold releasing step (step (d)), that is, a mold releasing force, has become an important problem. This is because if the mold releasing force is large, problems arise such as causing defects in the pattern and reducing the positioning accuracy due to lifting of the substrate from a stage.
One method for reducing the mold releasing force is a method of incorporating a photosensitive gas generating agent in a photocurable composition. This method is a method in which a gas generated when the photocurable composition is irradiated with light is caused to intervene between a mold and the photocurable composition to thereby reduce the mold releasing force by utilization of a pressure of the gas.
As photosensitive gas generating agents for nanoimprint lithography, for example, azo compounds, diazonium compounds, azide compounds, naphthoquinone compounds, sulfohydrazide compounds and hydrazo compounds, which are disclosed in Patent Literature 1, are known.